| | Conditions Treatments | ADD What does addemdum mean? Addendum is a noun which is defined as an addition to something that has already been written or produced, especially a book or law, or a supplement or something that is added, appended, or attached. ADD - Related Articles How to Use a Triangular Bandage What will happen if there is a blood clot blocking the aorta? How to Treat Pulled Calf Muscles How to Raise Your Body PH How to Avoid Hep C What are five major purposes of medical documentation? What are the tiny air sacs called in bronchi branches?